simple limb prosthesis process book

8/12/2019 Simple Limb Prosthesis Process Book

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Childs Trans-Femoral

(Above Knee) Prosthesis

Design Process Book

Designed forSimple Limb Initiativeby Kyle McCormick


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Simple Limb Initiative:

Colombia

Project Description Low end-user cost prosthesis


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Colombia is the worlds secondmost heavily land-mined country.Its total area is roughly twice thesize of California and the most

heavily mined areas are shownat left in red. The 3.6 million+landmines deployed sincethe 1960s claimed a recorded10,000+ victims since 1990

alone. The majority of thesevictims are children.

The Land Mine Toll


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Formative ResearchThere is a 41.9% dependencyratio in Colombia, meaning thata large chunk of the population

is made up of dependentyouth who need education andprovision for until they reachan age and ability to becomea self-sucient member of

society

Children of Colombia


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Income inequality in Colombia is some of the worstin the world, and despite being up almost 10%since 2008, there is still over 32% of the populationliving below the poverty level. Estimations are that

the poverty level in rural areas, where approximately1/4th of the population resides, is close to doublethat, with closer to 64% of the population living inpoverty thanks in large part to land displacementdue to violence, conict and the drug trade.

Rural Poverty

Colombias natural resources includepetroleum, natural gas, coal, ironore, nickel, gold, copper, emeralds,hydro power.

Only about 5% of Colombiasarable land is cultivated limited byharsh terrain and limited irrigation.

Agriculture and usable crops includecoee, corn, sugar/sugar cane,

bananas, fresh-cut owers, tobacco,

yucca, plantains, potatoes, cocoa,rice, cassava, sorghum, palm oil,

beans, and a few illicit plants. Resources

Bamboo isa plentiful,sustainableresource that isa strong buildingmaterial.


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Colorful CultureColombias ethnic diversity contributes a great dealto its unique culture, much of which revolves aroundits own Cumbiastyle of music which is a fusion of

African beat with that of native Colombian tribeswith a tinge of Caribbean-inuenced air as well as

many festivals of the Catholic faith of 90% of thepopulation.

Colombians love their sports. Soccer(ftbol) is of course the most widelyplayed and enjoyed pastime, and can beplayed by any able-bodied person in anyarea, even remote villages.

Sports and Pastimes


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Colombias extremely vaired and colorfulcrafts range from the ornate PastoLacquer; a layered natural resin and woodcombination that creates elaborate andextremely vivid colorful table wares tomoden Sombrero Vueltiao. Mola fabric is abright and beautifully woven textile of theKuna people, Ruana garments and pottery

are found in the people of Rquira, andthe elegant handcrafted bamboo Guaduafurniture is associated with the craftsmenof the Paisa region.

Handicrafts


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Distribution PartnerCatholic Church

Partner Benefts:

Wide reach Neutrality Safe Travel Volunteers Trust of locals

Catholic Relief Services isworking to deliver humanitarianaid to Colombians and their hostcommunities; meet needs for foodand non-food assistance; provide

psychological, social and legalassistance...-Catholic Relief Services


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Our Team Design Approach


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25% Local Material 25% 3D Printing

25% Mass Production25% Local Craftsman


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3D Printed

Mass Produced

Local Material

Mass Produced

Custom Made

Design Strategy

Custom Fit3D Printing-Socket

Mass Production- Joint

Local Material- Bamboo

Craftsman- Foot & Hand


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Knee Evolution

1

2

3

4

5

6

Bottom half of woodknee cracked.

Acrylic knee showedpromise.


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7 89

9

10

1112

9

10 11

Melted ABS knee v.1with reprint v.2

Acrylic knee v.2from solidblocks washighly functional.

Wood knee v.2cracked under load.


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Above Knee Prosthesis

Concept 1:

Wood Knee Joint

PVC Joinery

Bamboo Pylon

PVC Joinery

Polycarbonate Foot


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Polycarbonate, which wasmy rst material of choice

in constructing a foot, isboth hard to source inside

Colombia, and is notindistructable as our testingsurprisingly found.


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Concept 2:

Bamboo Pylon

PVC Joinery

Wood Veneer Foot


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Bent laminate wood fabricating was anew process to me, but turned out tobe pretty successful. It has potential

for application in a foot, but repeatedstress may cause the wood to crackand separate as some testing showed,and its a labor-intensive process that islimited in its shapes.


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Concept 3:

Bamboo Pylon

PVC Joinery

Bent Stainless SheetMetal Foot


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Learning to brazeto attach theankle adjustment

mechanism to therevised stainlessfoot.

Stainless steel footis easy to bendand fabricate andallows a durableshock absorbingfoot for natural gait.

Stainless Foot v.2


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3-axis adjustableknee inspired bychristmas tree stand.


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User Needs for Leg

Walk Forward

Walk Backward

Run

Ride Bike

Climb

Play / Sports

Terrain

Work in Field

Work at Home

Bath

0 1 2 3 4 5 6 7 8 9 10

ychological Needs 0 1 2 3 4 5 6 7 8 9 10 Aesthetic

Bamboo

Color

Pattern

Form

Metal Parts

Textile

0 1 2 3 4 5 6 7 8 9 10

Decision Matrix


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Fabrication

Heat treating bambooto strengthen. Creates

beautiful brown patina. 3D Printed ABS socketcan be printed in-country in one piece ortwo halves like this one.Incorporated patternallows airow to limb

as well as a wovenaesthetic.

Fabricating customstainless pivot hingesfor knee.


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Machining acrylic kneev.2 to accept hardware.

Bending nal stainless

foot v.3 to optimizewalking shape andsoccer toe.

Simulated powdercoating of hardward toappear less cold andmechanical.


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Bill of Materials1 -Custom 3D printed ABS socket~ $10 of material1 - Injection molded upper knee- $2.25/part @10,000 units*1 - Injection molded lower knee- $2.50/part @10,000 units*1 - 1.5 diameter bamboo pylon- locally sourced $ free1- Rubber foot tread - locally sourced from recycled bike tire $ free1 - 5x8 3/32 acrylic fairing -$.88 **8589K35 (out of 48x96)1 - 1.75 ID x1.5 16ga steel ankle tube -$.47 **7767T2911 - 5x1.5 30ga aluminum ankle shim -$.50 **9708K811 - Stainless sheetmetal foot (4x16 16ga) -$4.02 **8983K3552 - 1.5 12ga stainless brackets -$.20**8983K358

1 - 1.25 12ga stainless bracket$.08**8983K3583 - 5/16-8 x 2.75 socket cap screws - $1.69**91251A5941 - 5/16-8 x 1.75 socket cap screws -$.28 **91251A5898 - 8-32 x1/4 stainless cone point set screws $1.08 **92785A1904 - 5/16 Nylon locknuts - $.33**90715A0051 - 36x1.5 flat nylon webbing -$1.14 ***2 - 24x3/4 flat nylon webbing -$1.12 ***

1 - 1.5 Siderelease buckle - $.43 ***4 - 3/4 plastic slides- $.72Total

$28.14* price quotes based off (custompartnet.com) injection molded part estimator**denotes McMaster-Carr part number. These are retail prices reflectedabove, in volume I estimate approx. 1/4 the cost.

*** reflect bulk price from (strapworks.com)


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21.369

8.281

9.909

11.199

10.171

6.000

5.378

3.151

Orthographics


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1 -Custom 3D printed ABS socket

2 - Injection molded upper knee

3 - Injection molded lower knee

8 - 4x 5/16 sockethead cap screw

11 - 2x #4 x 3/4 sockethead cap screw

10 - 3 x 12ga stainless bracket

9 - 4x 5/16 nyloninsert locknuts

9 - 2x #4 nyloninsert locknuts

7 - 3 axis adj. ankle joint

4 - Bamboo pylon

6 - Stainless Foot

5 - Acrylic Fairing

Exploded Views


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Parts:

Tools:

(1) 5/16x 1.5

(1) #5 allen key

(3) 5/16x 2.75 (4) 5/16 locknuts

(2) #4 locknuts(2) #4x3/4

(2) 1.5bracke(1) 1.25bracket

(1) #2.5 allen key (1) small crescent wrench(1) #2 allen key


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Custom Parts:Individually scanned and printed

3D Socket for perfect fit


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Fabricated Parts:Hand bent 16ga stainless sheet foot

Templatefor footcutout

Bend points


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Assembly Instructions:

3D print socket.If printed in twopieces, epoxytogether.

Epoxy socket totop half ofincluded knee.

Insert 2 long boltsthrough the longbrackets and outerholes, through toouter bracket andlocknuts.

12 3

654

Insert 1 long boltthrough the bottomof short bracket inslot into locknut.Insert short boltthrough bracket intomid section andsecure with locknut.

Source 1.5 diabamboo pylon.

Insert into kneebottom and securewith two small #4socket screws and#4 locknuts.

Insert bamboo pyloninto ankle joint and

secure and adjustangle with 8 setscrews.

Attach fairing tofront of knee.


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Pre-assembly Pieces


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Fairing Options

The fairing represents a point of end-user customizability to tailor their prosthesis to their ownstyle and needs. It can function sans fairing, but may benet from some added protection

and air with one attached to its universal 2 diameter lower knee. This allows for quickly

fabricating a fairing out of 2 ID PVC pipe and covering it in cloth, leaving it bare, or even heat

bending a piece of laser cut acrylic.


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4-Bar linkage injection-molded knee. Allows forstability, natural gait andfull range of motion.

3 - axis adjustable ankle.Rotational, fore/aft, and side-to-sideindividualized adjustment controlledby set screws.

Final


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Context Shots:


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simple limb prosthesis process book

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